Question

A cistern can be filled by two pipes A and B in 12 minutes and 14 minutes respectively and can be emptied by third pipe C in 8 min if all the taps are turned on at the same moment, what part of the cistern will remain unfilled at the end of 7 min

Answer 1

Answer:

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Step-by-step explanation:

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Answer 2

Given :

A cistern can be filled by two pipes A and B in 12 minutes and 14 minutes respectively and can be emptied by third pipe C in 8 min

To find :

if all the taps are turned on at the same moment, what part of the cistern will remain unfilled at the end of 7 min

Solution:

A's 1 minute work =$\frac{1}{12}$

B's 1 minute work =$\frac{1}{14}$

C's 1 minute work = $\frac{1}{8}$

Their work together in 1 minute =$\frac{1}{12}+\frac{1}{14}-\frac{1}{8}=\frac{5}{168}$

Their work together in 7 minutes= $7 \times \frac{5}{168}=\frac{5}{24}$

Remaining work =$1 - \frac{5}{24}=\frac{19}{24}$

Hence 19/24 part of the cistern will remain unfilled at the end of 7 min